Spray nozzles having elliptical swirl chambers



SPRAY NOZZLES HAVING ELLIPTICAL SWIRL CHAMBERS Filed July 19, 1966Richard T. Mac Gu\r6CooPe.v

ATTORNEY United States Patent 3,394,889 SPRAY NOZZLES HAVING ELLIPTICALSWIRL CHAMBERS Richard Terence Macguire-Cooper, Boars Hill, Oxford,England, assignor to The Oxford Industrial Research and DevelopmentCompany, Boars Hill, Oxford, England, a partnership Filed July 19, 1966,Ser. No. 566,282 Claims priority, application Great Britain, Aug. 6,1965, 33,668/65; Aug. 8, 1965, 35,374/65; Oct. 27, 1965, 45,455/65; Feb.16, 1966, 6,744/66 9 Claims. (Cl. 239468) ABSTRACT OF THE DISCLOSUREThis invention relates to a new and improved nozzle, useful inconjunction with the dispensing of fluids contained within pressurizedcans or the like. In particular, this invention is directed to anelliptical swirl chamber having at least two foci, discharge meanscoupled to said chamber, and means for providing material to bedispensed to said swirl chamber.

This invention relates to the design and construction of a nozzle whichmay with advantage serve as an actuation or operating button in additionto its main function as a device for producing a fine spray whenconnected to the tubular stem of a valve fitted to a container of apressurized fluid or material.

The invention is principally concerned with those types of spray nozzlesor buttons used on what are often known as pressure packaging or aerosolsystems, and the invention refers to the type of nozzle known asmechanical break-up spray nozzles.

Such nozzles are at the present time produced in large numbers and aredesigned with such a configuration that a spray of very fine particlesis produced from fluids which are substantially non-volatile at ordinaryambient room temperatures, by the use of relatively low containerpressures. Such devices at present produced may incorporate a simplesystem wherein a pressure is produced inside the container by means of alow boiling point liquid which volatilises at room temperatures, or bythe introduction of a compressed gas charge into the container bysuitable mechanical means, and in this way can exert a pressure insidethe container thus acting as a simple propellent for the discharge ofthe contents of the container through a simple valve control system intothe atmosphere.

In the mechanical break-up nozzles in current use, the spray is producedby both mechanical and physical forces, often assisted by thesimultaneous vapourisation and expansion of any liquid propellent or gaswhich may pass into the nozzle.

The mechanism of the production of the spray production is one whereinthe contents of the container under the control of the discharge valvesystem are passed into the body of the nozzle and there enter a circularor cylindrical chamber by means of a feed passage system in which one ormore fluid feed passages merge substantially at a tangent to thecircular chamber, in a swirl chamber system.

In this manner the fluid entering the swirl chamber is given a swirlingor circular motion within the chamber.

A fine spray is produced by the discharge of the swirl chamber into asimple orifice in the wall of the swirl chamber, or a passage leading tosuch an orifice.

In this action a combination of the centrifugal and forward axialmovement of the discharging fluid in the swirl chamber or associateddischarge passage will on passing "ice through the discharge orificeserve to produce a very fine spray of fluid particles, due to amechanical shearing effect and/or the break-down of a fine film of fluidunder surface tension physical effects.

It has been noted that in such systems in current use the swirl chamberis circular in section, this being on first sight the most obvious shapeto produce a simple swirling motion.

The main object of the present invention is to produce an improveddesign and construction of nozzle, which will allow greater ranges ofspray production to be effected at low cost, and without the need todepart from the simple production methods at present employed in thesystems now utilized.

Thus according to the invention the use of swirl chambers of differentshapes will serve to promote different spray characteristics, and theuse of certain specified swirl chamber configurations will produce arange of spray characteristics which may be matched to formulationrequirements, thus allowing a range of nozzles to 'be produced withoutdeparting from a common outside shape, or departing from common orificeand passage or channel dimensions.

The swirl chamber shape to which this patent relates is that which maybe generally described as compound elliptical in shape, and anillustration of such a swirl chamber is shown in the accompanyingdrawings.

Such a swirl chamber may be moulded in one piece in a complex mouldingor may with advantage be produced by the assembly of one or moresuitable components, or may be formed in any suitable manufacturingprocess.

The walls of the swirl chamber need not be regular in dimension, and asa rule it should be possible to accommodate a circular shape inside thechamber in such a way that the area of the space so taken up will be thegreater part of the tot-a1 area.

The passages or channels which serve to feed the swirl chamber shouldwith advantage be so disposed that they are tangential to the circulararea of the swirl chamber.

Two of the walls of the swirl chamber should with advantage be flat, andthese walls will be those which contain and face the discharge orificeor passage.

It has been proved that any reduction in the energy required to producea fine spray can be a factor which will allow the container to work at alower and therefore safer pressure, irrespective of the saving in thecost of the propellent system, and this fact applies in particular tosprays produced by mechanical break-up spray nozzles.

According to the present invention, a swirl chamber will present acompound elliptical form which serves to minimise the laminarimpingement of currents moving in circular motion in the swirl chamberand would also serve to minimise the friction between the fluid inmotion and the Walls of the swirl chamber, and thus reduce energy lossesabsorbed in the swirling process.

It is also important in reducing energy loss at the point where thefluid stream from the feed passages or channels enter the swirl chamberby providing expansion space which will serve to limit interferencebetween streams of fluid already in motion within the chamber and thestream of fluid entering the chamber.

It is found that the walls of the chamber may with advantage tapertowards the wall containing the orifice or discharge passage, as thisreduction in effective diameter of the swirl chamber serves to increasethe velocity of the fluid as it moves towards the discharge orifice orpassage.

It has also been found that the conditions producing the dropletformation are improved by a uniform degree or turbulence at the orificearea immediately inside the swirl chamber, and the production of thisregular turbulent condition is assisted by the use of the ellipticalchamber. It has also been established that the use of regular ellipticalswirl chambers will have advantages in cases where two feed passages areused to feed the swirl chamber, and the degree of irregularity orcompounding of the swirl chamber shape can range over a wide variety ofelliptical shapes. According to the formulation of the contents of thecontainer, the use of elliptical swirl chambers will serve to reducekinetic energy loss in the nozzle, and will thus serve to promotegreater fluid stream momentum, leading to the production of greaterspray particle velocities without pressure increases in the formulation.

The use of the elliptical swirl chamber will reduce those factorsleading to the production of a vortex in the swirl chamber, and willassist in the promotion of regular uniform turbulent conditions and thusuniform spray patterns.

A further advantage of the use of the elliptical swirl chamber is thattheir use will delay propellent fluidgaseous changes of state in theswirl chamber and will thus release energy due to these changes of stateat the period of the droplet formation and film break-down when it canhave the greatest effect in producing a fine spray.

The effective diameter of an elliptical swirl chamber can be madesmaller than that of a normal circular swirl chamber due to theprovision of expansion spaces within the area immediate to the entry ofthe tangential streams, and this design factor can be used to limit thecentrifugal component and thus produce a spray which will have a greaterand more uniform mass flow per unit area, i.e. a spray with a lesshollow centre.

It has also been found that the use of the elliptical swirl chamber willlimit the production of hydrodynamic shock waves, and thus produce asmoother more uniform circular motion within the swirl chamber.

The use of this swirl chamber configuration has also certain advantagesin allowing the production of the nozzle when produced as a one-pieceplastic moulding, in that the swirl chamber forming tool core which isoften a projection of the tool core forming the tangential feedpassages, may be removed more easily, from the surrounding warm andsoft, resilient plastic body of the nozzle body due to the ellipticaland tapering configuration of the tool core forming the swirl chamberduring the moulding process, and this removal process is of greatadvantage in such difficult mouldings as those incorporating a feedpassage leading off-centre into a swirl chamber.

From a consideration of the above factors it may be seen that there areboth utilisation and production engineering advantages in the use of theelliptical or compound elliptical swirl chamber as applied to bothonepiece end assembled spray nozzles, and it is a factor in thisinvention that the use of variations on the configuration and dimensionsof the swirl chamber can be used to produce different spray patterns,velocities, or particle momentum without reference to alterations inother features of the nozzle, valve or formulation of the fluid to besprayed.

The invention will now be illustrated in the accompanying drawings, withvarious swirl chamber shapes and one embodiment of a one piece nozzletype in current use.

FIG. 1 is an outline illustration of a normal orthodox circulate, orcirculate cylindrical swirl chamber with the feed passages 1 merging ata tangent to the circular shaped swirl chamber cavity 2. A dischargeorifice 3 being formed in the centre.

FIG. 2 is an outline illustration of a compound elliptical swirl chamberwith two feed passages 4 leading initially into the expansion area ofthe swirl chamber 5 and then into the main body of the swirl chamberwhich contains the usual discharge orifice 7. Fluid entering the mainarea of the swirl chamber 6 will not interfere greatly with the fluidalready in circular swirling motion, and it is important to note in thecontext of this invention that limited swirling motion does start in theexpansion area 5. Thus :more uniform turbulent conditions areestablished in the main swirling cavity area 6.

FIG. 3 is an illustration of a normal one-piece nozzle at present incommon use whichmay be improved by the use of an elliptical swirlchamber the illustration shown being with or without the ellipticalchamber.

In this illustration the main nozzle body 8 contains a central cavity10. which fits in sealing engagement with the hollow valve stem 9.

A swirl chamber is formed inside the nozzle body at 14 with an offcentre passage leading tangentially into the swirl chamber from theprojection of the hollow nozzle cavity.

The swirl chamber 14 discharges to the outside of the nozzle by means ofa discharge passage and orifice 13. The whole being contained in acavity in the outer wall of the nozzle body 15.

FIG. 4 illustrates a compound elliptical swirl chamber which may withadvantage be used in the previous example nozzle, with the feed passageleading off centre and tangentially into the initial expansion area 17and then into the main chamber cavity area 18. prior to establishing adischarge outlet in the orifice 19.

FIG. 5 illustrates a section through the valve stem and nozzle body inthe area of the swirl chamber with the off-centre feed passage 22leading to the compound elliptical swirl chamber at a substantiallytangential angle 20 being a section of the nozzle body containing theswirl chamber, 21 being the elliptical swirl chamber, 22 being the offcentre feed passage, whilst 23 represents the valve stem.

FIG. 6 illustrates a plan view of the nozzle shown in FIG. 3. 24represents the valve stem feed passage, which is continued in feedeffect with a passage leading into the off-centre tangential feedpassage leading into the swirl chamber 26 from which the chamberdischarges through a passage and then through the discharge orifice 28,which is in a recess 29 formed in the outer surface of the nozzle body.

In the previous detailed description of the invention several differentways of utilising the invention have been described, but in all casesthe object of the invention is accomplished by the use of an ellipticalor compound elliptical swirl chamber with sides that taper towards theface containing the discharge passage or orifice.

The invention relates to in the main, the construction of one piecenozzles as used for the discharge of pressure packages or aerosols andallows the more efficient production of a fine spray or mist.

This invention has many advantages over established practice, and allowsthe simple and convenient production of the nozzle by pressure mouldingand ensures that a more efiicient production of a spray or mist may becarried out, without the use of ultra-high container pressures.

What we claim is:

1. An assembly for use with a pressurized container or the like, havinga valve with a valve stem having a liquid conveying passage,characterized in that a nozzle body is provided with a cavity which fitsin sealing engagement with the valve stem, an elliptically shaped swirlchamber having at least two distinct foci formed in the body, dischargemeans extending from said chamber to discharge material from said body,and a feed passage formed in said body and communicating with said swirlchamber and said passage in said stem.

2. An assembly according to claim 1, in which an expansion area isprovided in said body between said feed passage and said swirl. chamber.

3. An assembly according to claim 1, in which a plurality of feedpassages are provided which communicate with said swirl chamber and saidpassage in said stem.

4. An assembly according to claim 3, in which expansion areas areprovided between said feed passages and said swirl chamber.

5. In a device for use in a dispensing mechanism for a pressurizedcontainer or the like, and elliptical swirl chamber having at least twodistinct foci, discharge means coupled to said swirl chamber, and feedpassage means for providing material to said swirl chamber.

6. In a device according to claim 5, in which is provided one feedpassage means.

7. In a device according to claim 5, in which is provided a plurality offeed passages for directing material into the swirl chamber.

8. In a device according to claim 6, in which is provided an expansionarea between said swirl chamber and said feed passage.

9. In a device according to claim 7, in which expansion areas areprovided between said swirl chamber and said feed passages.

References Cited UNITED STATES PATENTS 1,716,174 6/1929 Klein 239468 X2,161,016 6/1939 Carr 239468 2,904,263 9/1959 Tate et al. 239468 X3,008,654 11/1961 Abplanalp et a1. 239468 3,075,708 1/1963 Cooprider239468 X 3,083,917 4/1963 Abplanalp et a1 239468 3,118,612 1/1964Abplanalp 239468 X 3,223,332 12/1965 .Nyden 239-579 X 3,236,031 2/ 1966Bennett et al. 239463 X M. HENSON WOOD, IR., Primary Examiner.

V. M. WIGMAN, Assistant Examiner.

